1. Field of the Invention
The present invention relates to a stationary original type image reader and particularly to a mounting structure for a drive circuit for the light source lamp.
2. Description of the Related Art
In image readers such as copying machines, scanners and the like, in which original image data which is displayed on a sheet of paper or the like is read and various processes are carried out, light beams emitted from a fluorescent lamp or other light source is irradiated onto the original. Reflected light beams are incident onto a light receiving station equipped with a photoelectric converter device such as CCD (Charge-Coupled Device) or the like. In the image reader of the original stationary type, while the light source lamp is moved with respect to the original which is placed on the platen glass, the light beams from the light source lamp irradiates the original. In addition, the optical path length from the original to the light receiving station must be kept even when the position of the original being irradiated varies. Reflectors provided for leading the reflected light beams to the light receiving station and an inverter circuit for operating the light source lamp must be moved together with the light source lamp along the original.
The inverter circuit and the light source lamp are mounted on a carriage which is movably provided in the casing of the image reader. A structure for mounting the inverter circuit on the carriage was previously proposed by the applicant of the present invention, in the image reader of Japanese Patent Application No. 11-263025. In this image reader, the inverter circuit is disposed at end portions of the carriage in the longitudinal direction thereof, and further the components of the inverter circuit are divided and disposed at both end portions.
It is sometimes necessary for the light source lamp or the inverter circuit to be replaced because they have reached their life span, or because they have been damaged. In image readers of the prior art, when the inverter circuit and the like have to be replaced, the carriage onto which they are mounted has to be removed from the main body of the image reader, and the part which is to be changed has to be removed from the carriage, and then replaced with the new part. This is because the inverter circuit board is fixed with screws onto the base plate of the carriage. Providing these screws on the roof plate of carriage, and fixing the inverter circuit board thereto has been considered, but the head portion of the screws protrude upward and thus it is necessary to provide a corresponding amount of space for the head portions of the screws, and the distance between the light source lamp and the original is increased, thus reducing the intensity of light which is radiated onto the original.
When the carriage is removed in order to replace the inverter circuit as described above, the wires connected to the carriage for operating the carriage must also be removed and thus the work of removing the circuits is very complex. In addition, when the inverter circuit is mounted once again into the main body, adjustments must be carried out and this further increases the difficulty of the work of replacing the inverter circuit.
Further, as in the image reader proposed in Japanese Patent Application No. 11-263025 , when the structure is such that component parts of the inverter circuit are divided and disposed at both end portions of the carriage, the respective component parts which have been divided have to be removed from both ends of the carriage, and thus the work of removing the circuits as well as the work of mounting them may be very complex.